NEW YORK (AP) — Pay attention. Stay focused. Be respectful. Be polite. Don't act bored. Or angry. Or distracted. Or sarcastic.

These might sound like simple principles, but it seems that candidates sometimes forget that during debates, they're being watched not just when they're speaking, but when they're listening.

And that's never been truer than this election season. Joe Biden's skeptical chuckles, President Barack Obama's copious note-taking, even Paul Ryan's thirsty gulps of water have become fodder for endless chatter, with a cultural shelf life possibly far longer than what these candidates were actually saying.

It's all been magnified by those constant split screens on TV. If it seems like they were used more than usual during the first two debates, it's because the candidates were so expressive — for better or worse — when they weren't speaking, says Marc Burstein, senior executive producer of political and live events coverage at ABC News.

"It was part of the story," Burstein says. "I shouldn't be in my job if I wasn't giving my viewers the opportunity to see that."

With the next debate upon us, here are a few tips from the experts on what to do when you're not the one talking.

Candidates! Are you listening?

THIS ISN'T A WRITTEN EXAM

Everyone jots down a note here and there. But it was duly noted that Obama looked like he was drafting a full speech during his first debate with Mitt Romney. Perhaps he felt it was a way to put the time to use. In any case, it hurt him.

"It can be perceived as being rude, inattentive, not really listening to what the other person is saying and being preoccupied with your own thoughts," says Lillian Glass, a body-language coach in Los Angeles. Of course, it's fine to jot down an occasional note, she says. "But when they consistently write while the other is speaking, it is disconcerting."

Biden may have gotten away with it because of his stature, age and experience, says Jonathan Paul, director of debate at Georgetown University. "Imagine if it wasn't the vice president but Paul Ryan who had been making those faces," says Paul. "I don't think the reaction would have been the same."

Glass, an author on body language, says that as a general rule, candidates "should never mug or make faces or have a condescending smile or laugh inappropriately. People are judging them by what they see, just as they're judging them by what they hear."

PAY ATTENTION

This sounds like a no-brainer, but there are nonverbal cues that can be interpreted as distracted, bored or impatient, which can seem perilously close to disrespectful. Remember George H.W. Bush's unfortunate glance at his watch in 1992? Remember Al Gore's sighs and eye-rolls in 2000? Did either of them win those elections?

"I tell my students all the time — the most important thing is to pay attention," says Paul, the Georgetown debate coach. "You have to appear as if you are listening and on top at every moment."

AND BE POLITE

Paul says he's had students who were excellent debaters but who would gasp or roll their eyes when hearing opponents' arguments. "People think nobody is paying attention to that — but they are," he says.

There is a way to demonstrate you are listening carefully, says Jerry Shuster, who teaches political communication at the University of Pittsburgh.

About that head-nodding: Be careful not to do too much of it, or you'll be seen as agreeing with your opponent's positions. That's a trap Obama seemed to fall into in the first debate, nodding in assent too many times for his supporters' liking.

Kathleen Hall Jamieson, a professor of political communication at the University of Pennsylvania, has a concise formula for such head-nodding.

"Candidates should avoid nodding in agreement to anything but statements praising our soldiers, complimenting their spouses and thanking the host school," she says.

HOW DO YOU INTERRUPT? VERY CAREFULLY

When and how to interrupt can be a minefield. You don't want to miss opportunities to rebut, but you can't be overly aggressive, either.

"If you want to interrupt or even disrupt the speaker, do so with authority but not a tone which denigrates the speaker," says Shuster. "Use a hand gesture while verbally signaling with a stock statement, like, 'I believe I need to stop you right there to respond or to react.' Above all, stay professional."

DONT DRINK THE WATER — WELL, NOT TOO MUCH

We all want our candidates to be well hydrated. That's why the glass of water is there.

But Ryan drank so often — undoubtedly a nervous tic rather than actual thirst — that it took up way too much attention. ("Saturday Night Live" spoofed him drinking so much during the debate that they eventually fed him with one of those hamster bottles.)

"I don't know Paul Ryan, but I assume he doesn't drink water every 15 seconds in everyday life," says Michael Levine, a veteran Hollywood publicist and debate watcher. "I might say to him, 'Son, it's fine to be hydrated, but that was a little much.'"

EVERYTHING IN MODERATION

All the experts agree that it's tough and delicate work to strike a balance between politeness and aggressiveness, passion and control.

But a good rule of thumb, says Paul, the Georgetown coach, is not to do too much of anything.

"I say to my students that people shouldn't notice you doing anything more than once," he says. "Because if they do, they will always find a negative."

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Associated Press writer David Bauder contributed to this report.

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Follow Jocelyn Noveck at http://twitter.com/JocelynNoveckAPAssociated PressCopyright 2012 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.

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